TENG-based self-powered sensing system and sleep wake-up method thereof

Abstract

According to the TENG-based self-powered sensing system and the sleep wake-up method thereof provided by the invention, through cooperation of the composite nano generator and the low-power-consumption Internet of Things technology, energy can be effectively collected in an all-weather manner, and acceleration data can be collected; the composite nanometer generator is formed by compactly combining a contact separation type friction nanometer generator and a solar cell, the space utilization rate is improved, and sunlight and mechanical vibration are used as energy sources. The friction nanometer generator is designed in a spring supporting mode, so that the durability is improved; the signal conditioning circuit is divided into two parts, one part is used for collecting and storing energy so as to realize self power supply; the other part is used for transmitting information carried by vibration so as to realize wake-up triggering of the low-power-consumption acceleration sensor; the system can realize self-powered and all-weather vibration monitoring, can be gradually applied to the fields of bridge health monitoring, air conditioner fan monitoring, iron tower monitoring and the like, and lays a solid foundation for realizing an IOT-based digital building technology in the future.

Description

Technical Field

[0001] The present invention relates to the field of measurement and testing technology, and in particular to a TENG-based self-powered sensing system and a sleep and wake-up method thereof. Background Art

[0002] Internet of Things (IoT) sensor nodes are widely used in the field of acceleration monitoring. Traditional sensor nodes often need to be powered by wires. There are disadvantages such as high deployment cost and difficult maintenance. Remote environments cannot even access the mains, which greatly limits the deployment of sensors. How to maintain energy supply under all-weather conditions has become the key to building the next generation of IoT technology. Here, we propose a composite power generation sensor system (A-GS) for acceleration sensing under all-weather conditions. The A-GS consists of a contact-separation friction nanogenerator (TENG), a solar panel, and a signal processing circuit. The TENG is both an energy harvesting device and a trigger signal source for acceleration sensing. The A-GS distributed on the surface of the acceleration sensor node can harvest energy from vibration and sunlight. The low-power IoT sensor node is divided into two paths: one is used for energy collection and management to realize power supply and energy storage, and the other is used to provide a microcontroller as a trigger signal for the sleep state after decoupling. Real-time acceleration information can be remotely transmitted and displayed on smartphones and computers, showing great potential in bridge monitoring, building exhaust system status monitoring, tower vibration monitoring and other fields. This work not only provides options for powering new sensors, but also promotes the practical application of Internet of Things technology.

[0003] The advancement of next-generation information technology, centered on the Internet of Things (IoT) and artificial intelligence, has become a key factor in promoting industrial upgrading. This progress is closely related to the strengthening of communication infrastructure. In the past few decades, the remarkable development of low-power electronic devices and wireless technology has promoted major innovations in IoT technology. These nodes effectively integrate information monitoring with information transmission.

[0004] With the continuous development of Internet of Things technology, IoT sensor nodes are widely used in the field of vibration monitoring. It has been applied in the fields of equipment health monitoring, building structure monitoring, logistics and transportation monitoring, and seismic monitoring. Especially in bridge monitoring, many sensor nodes collect and record parameters such as acceleration, strain, temperature, humidity, tilt angle, and precise positioning information of the bridge and transmit them back to evaluate the health of the bridge, timely maintain bridges that may have abnormalities, and ensure road safety. At the same time, IoT technology also plays an important role in the equipment health management of building air conditioning and exhaust systems and tower structure monitoring. However, traditional sensor nodes often need to be powered by wires. The power supply of wires has disadvantages such as high deployment cost, difficult maintenance, and large transmission loss, which makes the deployment of sensors very limited, especially in some remote environments or closed environments, and even in special situations such as being unable to access the mains.

[0005] In this sense, self-powered technology is an important research direction. It is of great significance to realize the self-powering of vibration sensors, that is, to use the energy collected from the environment to maintain the operation of the sensor. In recent years, a variety of energy harvesting technologies have been used for environmental energy collection and conversion, such as {wind power generation, water wave power generation, piezoelectric power generation}. These technologies have the characteristics of green source, convenient acquisition, safety and reliability in the process of natural energy collection. For example, Hao Cao et al. developed a hybrid wind energy harvesting system integrating piezoelectric and electromagnetic mechanisms to power low-power sensors on canyon bridges. Its maximum output power is only 19.24mW, which is difficult to meet the power requirements of traditional embedded devices. Trilochan Bhatta et al. invented a hybrid ellipsoid device for harvesting energy from the movement of water, and can monitor and transmit waveform information without external power supply. The design of the hybrid ellipsoid device is inspired by the elliptical trajectory of objects on shallow water waves. The device consists of six planar spiral coils that can cover waves in any direction to generate electricity. The device relies on waves, lacks environmental adaptability, and cannot work on land. Sooun Lee et al. proposed a design strategy for piezoelectric polyvinylidene fluoride-trifluoroethylene fiber and developed a communication system for self-powered motion sensing. The material is flexible and can only capture the energy generated by deformation, and has poor response to vibration. Lingfei Qi invented a portable wind and solar power generation system based on a foldable umbrella mechanism, which is installed in the middle of the highway. It can capture solar energy and wind energy generated by vehicles passing by at the same time. The application of these technologies has solved the inconvenience of obtaining energy in nature to a certain extent, but for acceleration / vibration sensing, the energy provided by vibration is not fully utilized. The friction nanogenerator (TENG) concept proposed by Academician Wang Zhonglin in 2012 based on the second component of Maxwell displacement current provides a new idea to solve this problem. TENG has the characteristics of simple structure, low cost, environmental friendliness, and the advantages of both power generation and sensing. The self-charging energy system based on TENG can provide power supply for electronic devices, but considering the problem of TENG power generation, solar energy is a better choice as an energy supplement.

[0006] Therefore, there is a need for a triboelectric nanogenerator that combines solar energy and can perform vibration monitoring. Summary of the invention

[0007] The present invention is to solve the self-power supply problem of vibration sensors, provide a self-powered sensing system based on TENG and its sleep awakening method, and an Internet of Things sensor node based on a composite power generation sensor system (A-GS), which can realize state perception under all-weather conditions. The node is composed of a composite nanogenerator (HNG), a microcontroller and peripheral circuits, and the A-GS is composed of a contact-separation friction nanogenerator (TENG), a solar cell (SC) and a signal conditioning circuit. Since TENG can be used as a trigger signal source and as an energy supplement for self-powered equipment, A-GS can not only collect energy in nature, but also transmit information carried by vibration; the power consumption of the sensor node can be controlled at about 50mW, which makes it possible to obtain enough energy to drive the sensor node from nature; by combining multiple energy supply forms such as solar energy and vibration, and cooperating with batteries for storage, the node is self-powered, laying a solid foundation for the realization of digital buildings in the future.

[0008] The present invention provides a self-powered sensing system based on TENG, comprising a composite nanogenerator, an energy management module and a trigger wake-up module electrically connected to the output end of the composite nanogenerator respectively, a battery charging module and a microcontroller unit electrically connected to the output end of the energy management module in sequence, an acceleration sensing module electrically connected to the output end of the trigger wake-up module, and a low-power Bluetooth module electrically connected to the microcontroller unit; another output end of the battery charging module is electrically connected to the acceleration sensing module, the acceleration sensing module is electrically connected to the microcontroller unit, and the microcontroller unit includes a sleep state and a working state;

[0009] The composite nanogenerator collects energy through sunlight and mechanical vibration and stores it in the battery charging module through the energy management module. At the same time, the mechanical vibration generates a trigger signal which is output to the trigger wake-up module. When the trigger signal reaches the threshold, the trigger wake-up module wakes up the microcontroller unit and the acceleration sensor module. The battery charging module supplies power to the microcontroller unit and the acceleration sensor module. The acceleration sensor module collects the acceleration data of the vibration and outputs it to the microcontroller unit, which is then sent through the low-power Bluetooth module.

[0010] The TENG-based self-powered sensing system described in the present invention, as a preferred embodiment, the composite nanogenerator includes a contact-separation friction nanogenerator, a solar cell and a signal conditioning circuit;

[0011] The contact-separation friction nanogenerator comprises an upper friction nanogenerator structure, a spring and a lower friction nanogenerator structure connected in sequence, wherein the upper friction nanogenerator structure comprises a first substrate and a first metal film connected to the bottom of the first substrate, the lower friction nanogenerator structure comprises a second substrate and a second metal film connected in sequence to the top of the second substrate, and a contact layer, the spring is connected to the four corners between the first substrate and the second substrate, the first metal film and the second metal film are connected by leads and connected to a signal conditioning circuit, and a solar cell is connected to the upper part of the first substrate; the signal conditioning circuit comprises a load;

[0012] When the contact layer and the first metal film rub against each other, the surface free energy of the contact layer changes, causing electrons to flow from a low free energy region to a high free energy region, forming a separation of positive and negative charges; when external vibration occurs, electrostatic induction causes the first metal film and the second metal film to carry different charges, and the external force causes the first metal film and the second metal film to perform periodic virtual tube contact and separation and generate periodic alternating current in the connected load;

[0013] The output end of the solar cell and the output end of the signal conditioning circuit are both connected to the energy management module.

[0014] The TENG-based self-powered sensing system described in the present invention is preferably configured such that the rebound of the spring can reduce the lateral displacement of the contact surface and reduce the wear of the contact layer.

[0015] The self-powered sensing system based on TENG described in the present invention is preferably configured such that the first substrate and the second substrate are both acrylic plates with a thickness of 5 mm, the first metal film and the second metal film are both copper films with a thickness of 0.025 mm, the contact layer is a FEP film with a thickness of 50 μm, and the spring is a stainless steel spring with a height of 1 cm;

[0016] The area of ​​the first substrate is the same as the area of ​​the second substrate;

[0017] The first metal film is bonded to the lower surface of the first substrate, the second metal film is bonded to the upper surface of the second substrate, the contact layer is bonded to the upper surface of the second metal film, and the solar cell is bonded to the upper part of the first substrate;

[0018] The first metal film and the second metal film are both electrically connected to the rectifier circuit of the energy management module through the electrode sheets.

[0019] In the TENG-based self-powered sensing system described in the present invention, as a preferred embodiment, the energy management module smoothes the output current of the contact-separation friction nanogenerator in the composite nanogenerator and stabilizes the voltage of the solar cell in the composite nanogenerator;

[0020] The trigger wake-up module includes a rectifier bridge electrically connected to the output end of the contact-separation friction nanogenerator, a capacitor C electrically connected to the output end of the rectifier bridge, and a comparator D electrically connected to both ends of the capacitor C;

[0021] When the voltage of capacitor C is greater than the set threshold, the output terminal of comparator D generates a trigger signal to activate the dormant microcontroller unit;

[0022] The trigger threshold can be adjusted by changing the reference voltage of comparator D.

[0023] In the TENG-based self-powered sensing system described in the present invention, as a preferred embodiment, the battery charging module charges the microcontroller unit and the low-power Bluetooth module;

[0024] The battery charging module is a chip BQ25504, and the 4.2V output end of the battery charging module is connected to the battery charging module, and the 3.3v output end is connected to the microcontroller unit and the low-power Bluetooth module.

[0025] The TENG-based self-powered sensing system described in the present invention, as a preferred embodiment, further includes a wired serial port electrically connected to the microcontroller unit;

[0026] The microcontroller unit is an MCU; the acceleration sensor module collects acceleration data and outputs it to the microcontroller unit after analog-to-digital conversion. The microcontroller unit processes and saves the acceleration signal and then sends it to the host computer through the low-power Bluetooth module and / or the wired serial port. The low-power Bluetooth module also includes a sleep state and a working state.

[0027] When the trigger signal output by the trigger wake-up module disappears, the microcontroller unit immediately enters the stop mode after sending the current data, and at the same time operates the low-power Bluetooth module to enter the shutdown mode. At this time, the self-powered sensor system enters the sleep state.

[0028] The TENG-based self-powered sensing system described in the present invention is, as a preferred method, a low-power Bluetooth module uses an NB-LOT module to link to the 4 / 5G network provided by the operator, and the low-power Bluetooth module outputs to a host computer, and the host computer is installed with LABVIEW software.

[0029] The present invention provides a sleep awakening method for a self-powered sensing system based on TENG, which is characterized by comprising the following steps:

[0030] S1. When the contact-separation friction nanogenerator in the composite nanogenerator captures vibration, the upper friction nanogenerator structure and the lower friction nanogenerator structure of the contact-separation friction nanogenerator contact and separate under the elastic force of the spring, generate charge transfer under the action of electrostatic induction and output current to the trigger wake-up module and the energy management module respectively. The energy management module smoothes the output power and outputs it to the battery charging module for storage. The solar cell in the composite nanogenerator receives solar energy and outputs it to the energy management module. The energy management module performs voltage stabilization and outputs it to the battery charging module for storage.

[0031] When the vibration reaches the untriggered threshold, the microcontroller unit is in a dormant state;

[0032] When the vibration reaches the trigger threshold, the trigger wake-up module collects the trigger wake-up signal and outputs it to the microcontroller unit to wake up the microcontroller unit. At the same time, the battery charging module provides power to the microcontroller unit and the acceleration sensor module, and then enters step S2;

[0033] S2, the acceleration sensor module collects acceleration data and outputs real-time acceleration data to the microcontroller unit after analog-to-digital conversion. The microcontroller unit processes and saves the data and sends it to the host computer through the low-power Bluetooth module and / or the limited serial port. When the vibration intensity drops below the set threshold, enter step S3;

[0034] S3, the trigger wake-up signal disappears, the microcontroller unit immediately enters the stop mode after sending the current data, and at the same time operates the low-power Bluetooth module to enter the shutdown mode, enters the sleep state, and returns to step S1.

[0035] The present invention provides a self-powered sensing system based on TENG, and the self-powered sensing system is applied to vibration monitoring.

[0036] The TENG-based self-powered sensing system described in the present invention is preferably applied to bridge health monitoring, air conditioning fan monitoring and tower monitoring.

[0037] The present invention has the following advantages:

[0038] Through the combination of A-GS composite power generation technology and low-power IoT technology, energy can be effectively collected and acceleration data can be collected all day long. As the energy core of A-GS, the compact combination of TNEG and SC improves the utilization of space and collects energy through sunlight and mechanical vibration. In order to improve the durability of TENG, the friction nanogenerator is designed in the form of spring support. The signal conditioning circuit is divided into two parts, one for energy collection and storage to achieve self-power supply; the other part is used to transmit the information carried by vibration to achieve the wake-up trigger of the low-power acceleration sensor. The lower computer made of STM32L4 series microcontroller has a proper wake-up mechanism and good low-power consumption characteristics. Considering the versatility and compatibility, and in order to improve the degree of visualization, LABVIEW software is used to make the upper computer for data display and storage. Finally, under the condition of self-power supply and all-weather, the acceleration information collected by the sensor is displayed on the computer and mobile phone through the cloud server. A-GS module and low-power IoT module will be gradually applied in the fields of bridge health monitoring, air conditioning fan monitoring, tower monitoring, etc. Our work not only provides a strategy for developing self-powering methods for next-generation multifunctional sensor nodes, but also lays a solid foundation for the realization of future IOT-based digital building technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of some application scenarios of a self-powered sensing system based on TENG and its sleep wake-up method;

[0040] Figure 2a A schematic diagram of the contact-separation friction nanogenerator structure of a TENG-based self-powered sensing system;

[0041] Figure 2b An exploded diagram of a contact-separation friction nanogenerator for a self-powered sensing system based on TENG;

[0042] Figure 2c A schematic diagram of the contact-separation friction nanogenerator structure of a TENG-based self-powered sensing system;

[0043] Figure 3a A schematic diagram of TENG open circuit voltage of a TENG-based self-powered sensing system and its sleep wake-up method;

[0044] Figure 3b A schematic diagram of TENG short-circuit current of a TENG-based self-powered sensing system and its sleep wake-up method;

[0045] Figure 3c A schematic diagram of a TENG-based self-powered sensing system and its sleep wake-up method, TENG, and charge transfer;

[0046] Figure 3d A schematic diagram of a TENG-based self-powered sensing system and its sleep wake-up method showing the change of TENG current with squeezing force;

[0047] Figure 3e A schematic diagram of impedance matching of a self-powered sensing system based on TENG and its sleep wake-up method;

[0048] Figure 3f A schematic diagram of impedance matching resistance of a self-powered sensing system based on TENG and its sleep wake-up method;

[0049] Figure 3g A schematic diagram of the durability of a TENG-based self-powered sensing system and its sleep wake-up method;

[0050] Figure 4 A schematic diagram of the relationship between the modules of a TENG-based self-powered sensing system and its sleep wake-up method;

[0051] Figure 5 A schematic diagram of charging curves of capacitors with different capacities for a self-powered sensing system based on TENG and its sleep wake-up method;

[0052] Figure 6a A schematic diagram of a trigger circuit of a self-powered sensing system based on TENG and its sleep wake-up method;

[0053] Figure 6b A schematic diagram of switching between system states of a self-powered sensing system based on TENG and its sleep and wake-up method;

[0054] Figure 6c A schematic diagram of power consumption of a self-powered sensing system based on TENG and its sleep wake-up method;

[0055] Figure 6d A schematic diagram of the test results of a self-powered sensing system based on TENG and its sleep wake-up method;

[0056] Figure 7a Schematic diagram of a TENG-based self-powered sensing system and its sleep wake-up method for placing nodes on the bridge surface;

[0057] Figure 7b A schematic diagram of acceleration test results of a self-powered sensing system based on TENG and its sleep wake-up method;

[0058] Figure 7c A schematic diagram of a self-powered sensing system based on TENG and its sleep wake-up method for application in a tower;

[0059] Figure 8a A schematic diagram of the vibration triggering time of different frequencies for a self-powered sensing system based on TENG and its sleep wake-up method;

[0060] Figure 8b A schematic diagram of different pressure vibration triggering times of a TENG-based self-powered sensing system and its sleep wake-up method;

[0061] Fig. 9 This is a flow chart of a sleep wake-up method for a self-powered sensing system based on TENG.

[0062] Reference numerals:

[0063] 1. Composite nanogenerator; 11. Contact-separation friction nanogenerator; 111. Upper friction nanogenerator structure; 1111. First substrate; 1112. First metal film; 112. Spring; 113. Lower friction nanogenerator structure; 1131. Second substrate; 1132. Second metal film; 1133. Contact layer; 12. Solar cell; 2. Energy management module; 3. Trigger wake-up module; 4. Battery charging module; 5. Microcontroller unit; 6. Acceleration sensor module; 7. Low-power Bluetooth module. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0065] Example 1

[0066] A self-powered sensing system based on TENG and its sleep wake-up method, some application scenarios such as Figure 1 As shown, the structure of the composite nanogenerator is as follows Figure 2a to 2cAs shown, the 3D printed resin shell is used to accommodate the composite nanogenerator (HNG) 1 designed by us. The HNG consists of a contact-separation friction nanogenerator TENG11 and a solar cell SC12, where SC12 is installed on the upper surface of TENG11 to effectively utilize the idle space of the device. The FEP film 1133 is an excellent insulating material with the characteristics of small dielectric constant and high surface resistance. It also has certain mechanical strength and excellent chemical stability. Therefore, the contact structure based on the FEP film 1133 can effectively overcome the performance degradation caused by repeated contact separation. The TENG module 11 consists of two acrylic plates 1111 and 1131 installed symmetrically from top to bottom, as well as attached Cu films 1112 and 1132, FEP film 1133 and electrodes. Two acrylic plates of equal area are used as substrates, copper is used as the inner layer material and is attached to the two acrylic plates 1111 and 1131 respectively, and the FEP film 1133 is used as a contact layer and is attached to one of the Cu films 1132. The two acrylic plates are connected by a spring 112 to form a contact-separation structure between the two poles.

[0067] The working principle of TENG (triboelectric nanogenerator)11 is as follows Figure 2c As shown. When two objects rub against each other, the surface free energy of the contact layer will change, causing electrons to flow from the low free energy area to the high free energy area, forming a separation of positive and negative charges. These separated charges will accumulate on the surface of the contact layer, and at the same time be introduced into the external circuit through the charge collection layer to generate current. When the two electrodes are relatively stationary, there is no potential difference between the two poles, and no charge transfer occurs. When the upper and lower electrode plates 111, 113 are in contact and separation under the action of external force, due to electrostatic induction, the upper and lower electrode plates 111, 113 will carry different charges. The potential difference between the two electrode plates 111, 113 increases, and charge transfer occurs. Under the action of external force, the two electrodes are brought into contact and separated at a certain period. If a load is connected between the two electrodes, a periodic alternating current will be generated in the load.

[0068] This technical solution uses the current generated by TENG11 as a trigger signal for vibration wake-up measured by the sensor. When the vibration reaches a certain threshold, the vibration wake-up is triggered. The TENG11 signal is collected as a trigger wake-up signal. When the vibration exceeds a certain threshold, MCU5 wakes up MCU5 according to the detected trigger signal to achieve the goal of reducing power consumption. At the same time, the solar panel provides power for the system, and the excess power will be stored in the battery.

[0069] In reality, the vibration of buildings is very complex, and ordinary energy conversion methods cannot convert such vibrations. Therefore, in order to verify the feasibility of the TENG module to collect such mechanical vibration energy, a stepper motor with adjustable frequency and amplitude was used to study the output characteristics of the TENG module under a sliding displacement of 40mm. The TENG open circuit voltage (V), short circuit current (I), and transfer charge (C) were evaluated under conditions close to the natural vibration frequency (2Hz). Figure 3a-3c As the two plates move relative to each other, the voltage, current, and charge characteristics all show periodic changes. The maximum output voltage of TENG can reach 200V, and the current can reach 3μA. Figure 3d It shows that when the vibration frequency is 2Hz, the TENG current increases with the increase of the squeezing force, which can be explained by the following mechanism: when the initial distance between the two plates is different, the greater the relative movement distance, the stronger the induction charging and the greater the voltage. (Impedance matching, Figure 3e~3f ): Considering that 2 Hz is closer to the vibration of the building, we then tested the output characteristics of TENG at this frequency, such as Figure 3f As shown in the figure, the results show that the best matching resistance of TENG is 14MΩ, the operating frequency is 2Hz, the instantaneous maximum output power is 0.45mW, and the power shows a trend of first increasing and then decreasing as the load resistance increases. Therefore, in order to obtain the best output, the input resistance of the external load should be matched to about 14MΩ. To evaluate the material loss of the friction layer, we compared the output voltage before and after 20,000 cycles under 3Hz vibration, and it can be observed that, Figure 3g As shown in the figure, after 20,000 cycles, the voltage did not drop significantly, so the TENG has excellent durability during long-term use. The excellent durability of the contact-separation TENG comes from the flexible spring design. The spring rebound reduces the lateral displacement of the contact surface and can significantly reduce the wear of the FEP film. Therefore, TENG can be used to collect mechanical energy in building vibration monitoring systems.

[0070] Combination Figure 3e We believe that the maximum power generated by TENG is only 0.45mW, which is difficult to meet the needs of self-powering the device and charging the battery. Therefore, we added solar cells to the design of A-GS to collect light energy as energy supplement. <guarci>We also evaluate the performance of the solar cell model, including its open circuit voltage (V), short circuit current (I), and transfer charge (C). Figure 3g As shown in the figure, under low light conditions, as the light intensity increases, the voltage rises faster. After reaching the strong light area, the voltage tends to be stable and stabilizes at 6.68V. The current has a tendency to rise first and then fall. The maximum current appears at 4000lx, which is 15.48mA. A solar cell is a photoelectric element that can convert energy. It is made of P-type and N-type semiconductors. Its basic structure is a large-area PN junction. When the light energy absorbed by the solar cell exceeds its band gap energy, these photons can excite electrons to jump from the valence band to the conduction band and leave holes in the valence band to form electron-hole pairs. These electron and hole pairs are then separated by the electric field inside the semiconductor, and the electrons flow to the negative electrode of the battery and the holes flow to the positive electrode of the battery, thereby generating current. When the voltage of the solar cell reaches a certain value, it enters the voltage saturation region, and the equivalent internal resistance of the solar cell begins to increase, resulting in the output current being limited, so the current shows a slight decrease. By multiplying the voltage and current, we can get the output power curve of solar energy. It can be observed that the maximum power output appears at 2000lx. At the same time, under the intensity of sunlight, the power is not less than 50mW, which can meet the needs of self-powering and charging of the equipment.

[0071] Design and Implementation of A-GS

[0072] This technical solution develops A-GS by integrating the required low-power functional modules. Figure 4 The relationship between the modules of A-GS is shown. A-GS consists of a composite friction nanogenerator 1, an energy management module 2, a trigger wake-up module 3, a battery charging module 4, a microcontroller unit 5, an acceleration sensor module 6, and a low-power Bluetooth module 7. The green process (upper arrow) and the yellow process (lower arrow) represent the energy direction and the signal direction respectively. In A-GS, the electrical signal generated by the composite nanogenerator 1 has two directions. One direction passes through the energy management module 2 and the battery charging module 4 to provide power to the entire node and store excess energy; the other direction passes through the trigger wake-up module 3. Under certain conditions, a trigger wake-up signal is generated to wake up the acceleration sensor 6, collect acceleration data, and send a signal through the Bluetooth module 7. MCU5 plays the role of state perception, control coordination, and data processing.

[0073] exist Figure 4 In the first line, TENG11 always exhibits the characteristics of high voltage and low current when capturing natural vibrations, which is not conducive to energy capture. At the same time, since the electrical signal generated by SC12 is low-voltage direct current and has huge differences in the signal characteristics of TENG11, the two cannot be directly connected in parallel or series to provide current. The electrical signals of both need to be processed before they can be connected to the node for power supply. The output of TENG11 is alternating current and has the characteristics of large instantaneous power changes. The energy management module 2 is required to smooth its output power and fill the peaks for use in subsequent circuits. The power output of SC12 can quickly charge a 100μF capacitor, but the output voltage will drop rapidly when connected to the load, which is difficult to meet the requirements of voltage-stabilized power supply. Therefore, SC12 must be processed by the voltage-stabilizing circuit before it can power subsequent equipment.

[0074] The battery charging module 4 uses the energy harvesting chip BQ25504, which supports boost charging of the lowest static ultra-low current of 330nA, can manage the output power generated by various DC sources such as solar energy 12 and friction nanogenerator (TENG) 11, and has charging protection, provides battery status information, and can output after the voltage reaches the standard. The input end of BQ25504 is connected to HNG1, and the 4.2V output end is connected to the rechargeable battery. When the battery is fully charged, the battery is charged. The 3.3v output end is connected to the MCU, and a stable voltage output is provided for the sensor and Bluetooth module. Figure 5 The charging curves of capacitors with different capacities of SC and TENG under the management of BQ25504 module are shown. The charging voltage of capacitors with different capacities of [1-470F] is finally stabilized at 4V. In summary, the energy management module can improve the charging efficiency and speed up the charging speed; the battery charging module can stabilize the output voltage.

[0075] exist Figure 4 In the second circuit, in order to extract the motion information carried by TENG11 during power generation, we designed a trigger wake-up module 3. When the acceleration exceeds a certain value, the wake-up module 3 outputs the trigger wake-up information to MCU5, and acts on the acceleration sensor to start collecting acceleration data. Figure 6a As shown, the signal first passes through a rectifier bridge and becomes a DC signal. The DC signal charges a capacitor and leads the voltage across the capacitor to the comparator. By changing the reference voltage of the comparator, an adjustable trigger threshold is achieved. When the capacitor voltage is greater than the set threshold, a trigger signal is generated at the output of the comparator to activate the dormant MCU5. Through this intermittent work, the average power of the node can be greatly reduced to achieve energy saving. After the acceleration signal is processed and saved by MCU5, it is sent to the host computer through the low-power Bluetooth module in a specific format. The low-power Bluetooth module also participates in the dormancy in the low-power state to achieve energy saving.

[0076] Building a low-power IoT node

[0077] In order to minimize the power consumption of the device, the device needs to enter the sleep state during the work interval, and complete the conversion between the sleep state and the working state with the cooperation of A-GS. For this reason, we designed a low-power embedded node that can be triggered. The node consists of an MCU main control module 5, an acceleration sensor module 6, a Bluetooth communication module 7 and a host computer. The MCU main control module 5 is the control core of the entire system. By coordinating the work of the other modules, it realizes the data acquisition and transmission tasks and the switching between the sleep state and the working state; the acceleration sensor module 6 mainly completes the acquisition and analog-to-digital conversion of acceleration data, and outputs real-time acceleration data to the main control module 5; the collected data is transmitted to the host computer through a wired serial port connection or a wireless Bluetooth module 7, and the host computer uses the LBVIEW platform to process, graphically display and save the acceleration data.

[0078] In order to minimize the power consumption of the node, when the trigger signal disappears, MCU5 will immediately enter the stop mode after sending the current data, and operate Bluetooth 7 to enter the shutdown mode. At this time, the system power consumption is the lowest and enters the sleep state. Figure 6b We tested the power consumption of the system in different states. Figure 6c The test results are shown in Figure 6d As shown, when MCU5 is running in running and standby modes, relatively high and low currents are required, about 33.2 and 2.23 mA, respectively. When communicating with the outside world, that is, when BLE is working, there is also high energy consumption.

[0079] Build a remote monitoring network for buildings

[0080] With the development of IOT technology, data is no longer limited to local storage, but can be transmitted to computers wirelessly for remote monitoring. In this work, we aim to break the barriers between traditional single-chip microcomputers and IoT platforms, and design a remote monitoring network based on A-GS for state perception under remote conditions. The nodes are placed on the surface of the building to be tested, and the A-GS provides energy for the nodes and also serves as a trigger source. The deployment of the wireless sensor network depends on the basic operator network, and uses NB-LOT modules to link to the 4 / 5G network provided by the operator.

[0081] Due to the close cooperation between A-GS and MCU5, the node has adaptability to various environments. It can be used for structural monitoring of bridges, wind turbines and towers. Figure 7a As shown in the figure, the node is placed on the bridge surface. Under the action of light and vibration, A-GS collects energy and stores it in a capacitor (or rechargeable battery). As the vibration intensifies, the low-power trigger module outputs a trigger signal, the MCU is awakened and enters the working state, and the real-time acceleration value is collected by the sensor and sent to the host computer by the low-power Bluetooth module. The data is as follows Figure 7b As shown in the figure. The acceleration curve drawn by LABVIEW can be transformed into vibration frequency and other information through fast Fourier transform, which provides a basis for bridge maintenance. Figure 7c The application of monitoring nodes on towers was demonstrated. Similar to bridge monitoring, the nodes captured the vibration signals of the towers and calculated the accumulated vibrations. In this way, they could issue an alarm when the bolts might be loose and arrange inspections and maintenance in a timely manner.

[0082] like Figure 8a-8b The results shown are the results of different pressure frequency settings of the stepper motor that applies vibration to the friction nanogenerator 11. Figure 8a It is the time to reach the trigger threshold (1.2v) at the same squeezing force of 25N and different vibration frequencies. Figure 8b It is the time it takes to reach the trigger threshold (1.2v) when vibrating at the same frequency under different squeezing forces.

[0083] With the introduction of Industry 4.0, the emergence of high-standard factory buildings and the improvement of factory intelligence, in order to grasp the fault status of ventilation / air conditioning systems in real time, the fans located outside the building can be included in the monitoring range. The application of the designed self-powered sensor in building fan monitoring will demonstrate its unique role. When a fan fails, the nodes installed on the fan can interactively identify, process, and remotely transmit specific signals, so that maintenance personnel can receive alarm information and take repair measures in the first time. More importantly, this work not only provides a case for the Industrial Internet of Things, but also promotes the industrialization of self-powered nodes.

[0084] The present invention can effectively collect energy and acceleration data around the clock through the combination of A-GS composite power generation technology and low-power Internet of Things technology. As the energy core of A-GS, the compact combination of TNEG11 and SC12 improves the utilization of space, and collects energy through sunlight and mechanical vibration. In order to improve the durability of TENG11, the friction nanogenerator 11 is designed in the form of spring 112 support. The signal conditioning circuit is divided into two parts, one part is used for energy collection and storage to achieve self-power supply; the other part is used to transmit the information carried by the vibration to achieve the wake-up trigger of the low-power acceleration sensor. The lower computer made of STM32L4 series microcontroller has an appropriate wake-up mechanism and good low-power consumption characteristics. Considering the versatility and compatibility, and in order to improve the degree of visualization, LABVIEW software is used to make the upper computer for data display and storage. Finally, under the self-powered and all-weather conditions, the acceleration information collected by the sensor is displayed on the computer and mobile phone through the cloud server. A-GS module and low-power Internet of Things module will be gradually applied in the fields of bridge health monitoring, air conditioning fan monitoring, tower monitoring, etc. Our work not only provides a strategy for developing self-powering methods for next-generation multifunctional sensor nodes, but also lays a solid foundation for the realization of future IOT-based digital building technologies.

[0085] The shell of the A-SG in the present invention is a rectangular parallelepiped without a top cover, which is made of photosensitive resin by 3D printing. The top is a contact-separation type friction nanogenerator 11. The upper surface of the friction nanogenerator 11 is covered with a solar panel 12 of the same size.

[0086] For the contact-separation TENG11, first, the copper film 1112\1132 is covered on the surface of two 10cm×10cm acrylic plates 1111\1131, and then a piece of FEP film 1133 with a thickness of 50μm is pasted on the copper 1132 surface of one of the acrylic plates 1131. Conductive cloth is used as the electrode material, and about 3cm long is drawn from the copper film 1112\1132 of the two acrylic plates. The two opposite acrylic plates 1111\1131 are connected at the four corners with four springs 112.

[0087] A programmable electrometer (instrument model 6514) was used to measure the output of the composite nanogenerator, including open-circuit voltage, short-circuit current, transferred charge, and capacitor voltage. The LabVIEW 2021 software platform was used to collect, display, and save the data transmitted by the electrometer in real time. A linear motor (LinMot MBT-37120) simulated reciprocating motion to accurately control the frequency and amplitude of the TENG module. A digital power meter (GPM-8310) was used to measure the power of each module. The solar output was tested under different light intensities using the simulated solar spectrum of the Z-Park CEL-S500 solar simulator. The solar intensity was measured by a irradiance meter (CEL-FZ-A). The PCB module was designed using Altium Designer.

[0088] In order to fully evaluate whether the device we designed can be effectively awakened from sleep mode and enter normal working state, we conducted a series of detailed experiments. Fig. 9 As shown in the figure, in the experiment, we started the linear motor and simulated vibration environments of different intensities by gradually increasing its movement frequency, and then gradually reduced the frequency to observe the response of the device. During this process, we used the analog-to-digital conversion (ADC) unit integrated on the A-GS device to accurately collect the voltage values ​​of the trigger signal and the wake-up signal.

[0089] From the experimental data, we can clearly observe that as the vibration intensity gradually increases, the trigger source signal generated by the friction nanogenerator (TENG)11 also increases. This enhanced signal successfully stimulates the wake-up mechanism of the device and generates a corresponding wake-up signal. This observation shows that our device can effectively respond to external vibration stimuli and initiate the wake-up procedure.

[0090] Furthermore, when the vibration intensity drops below the set threshold, the wake-up signal disappears and the A-SG (assuming it is a specific device module) re-enters the dormant state. The A-SG has the characteristics of sensitivity, accuracy and energy saving. In the absence of sufficient external stimulation, the device can automatically return to low-power mode to extend its service life.

[0091] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.< / guarci>

Claims

1. A self-powered sensing system based on TENG, characterized in that: The invention comprises a composite nanogenerator (1), an energy management module (2) and a trigger awakening module (3) electrically connected to the output end of the composite nanogenerator (1), a battery charging module (4) and a microcontroller unit (5) electrically connected to the output end of the energy management module (2), an acceleration sensor module (6) electrically connected to the output end of the trigger awakening module (3), and a low-power Bluetooth module (7) electrically connected to the microcontroller unit (5); the other output end of the battery charging module (4) is electrically connected to the acceleration sensor module (6), the acceleration sensor module (6) is electrically connected to the microcontroller unit (5), and the microcontroller unit (5) comprises a dormant state and an operating state; The composite nanogenerator (1) collects energy through sunlight and mechanical vibration and stores it in the battery charging module (4) through the energy management module (2). At the same time, the mechanical vibration generates a trigger signal which is output to the trigger wake-up module (3). When the trigger signal reaches a threshold, the trigger wake-up module (3) wakes up the microcontroller unit (5) and the acceleration sensor module (6). The battery charging module (4) supplies power to the microcontroller unit (5) and the acceleration sensor module (6). The acceleration sensor module (6) collects acceleration data of the vibration and outputs it to the microcontroller unit (5), which is then sent through the low-power Bluetooth module (7).

2. According to claim 1, a self-powered sensing system based on TENG is characterized in that: The composite nanogenerator (1) comprises a contact-separation friction nanogenerator (11), a solar cell (12) and a signal conditioning circuit; The contact-separation friction nanogenerator (11) comprises an upper friction nanogenerator structure (111), a spring (112) and a lower friction nanogenerator structure (113) which are connected in sequence; the upper friction nanogenerator structure (111) comprises a first substrate (1111) and a first metal film (1112) connected to the bottom of the first substrate (1111); the lower friction nanogenerator structure (113) comprises a second substrate (1131) and a second metal film (1132) connected in sequence to the top of the second substrate (1131), and a contact layer (1133); the spring (112) is connected to the four corners between the first substrate (1111) and the second substrate (1131); the first metal film (1112) and the second metal film (1132) are connected by leads and are connected to the signal conditioning circuit; the solar cell (12) is connected to the upper part of the first substrate (1111); the signal conditioning circuit comprises a load; When the contact layer (1133) and the first metal film (1112) rub against each other, the surface free energy of the contact layer (1133) changes, causing electrons to flow from a low free energy region to a high free energy region, thereby forming a separation of positive and negative charges; When external vibration occurs, electrostatic induction causes the first metal film (1112) and the second metal film (1132) to carry different charges, and the external force causes the first metal film (1112) and the second metal film (1132) to perform periodic virtual tube contact and separation and generate periodic alternating current in the connected load; The output end of the solar cell (12) and the output end of the signal conditioning circuit are both connected to the energy management module (2); The rebound of the spring (112) can reduce the lateral displacement of the contact surface and reduce the wear of the contact layer (1133).

3. According to claim 2, a self-powered sensing system based on TENG is characterized in that: The first substrate (1111) and the second substrate (1131) are both acrylic plates with a thickness of 5 mm, the first metal film (1112) and the second metal film (1132) are both copper films with a thickness of 0.025 mm, the contact layer (1133) is a FEP film with a thickness of 50 μm, and the spring (112) is a stainless steel spring with a height of 1 cm; The area of ​​the first substrate (1111) is the same as the area of ​​the second substrate (1131); The first metal film (1112) is bonded to the lower surface of the first substrate (1111), the second metal film (1132) is bonded to the upper surface of the second substrate (1131), the contact layer (1133) is bonded to the upper surface of the second metal film (1132), and the solar cell (12) is bonded to the upper part of the first substrate (1111); The first metal film (1112) and the second metal film (1132) are both electrically connected to the rectifier circuit of the energy management module (2) via electrode sheets.

4. According to claim 1, a self-powered sensing system based on TENG is characterized in that: The energy management module (2) smoothes the output current of the contact-separation friction nanogenerator (11) in the composite nanogenerator (1) and stabilizes the voltage of the solar cell (12) in the composite nanogenerator (1); The trigger awakening module (3) comprises a rectifier bridge electrically connected to the output end of the contact-separation friction nanogenerator (11), a capacitor C electrically connected to the output end of the rectifier bridge, and a comparator D electrically connected to both ends of the capacitor C; When the voltage of the capacitor C is greater than a set threshold, the output terminal of the comparator D generates a trigger signal to activate the dormant microcontroller unit (5); The trigger threshold can be adjusted by changing the reference voltage of the comparator D.

5. The self-powered sensing system based on TENG according to claim 1, characterized in that: The battery charging module (4) charges the microcontroller unit (5) and the low-power Bluetooth module (7); The battery charging module (4) is a chip BQ25504, the 4.2V output end of the battery charging module (4) is connected to the battery charging module (4), and the 3.3V output end is connected to the microcontroller unit (5) and the low-power Bluetooth module (7).

6. The self-powered sensing system based on TENG according to claim 1, characterized in that: It also includes a wired serial port electrically connected to the microcontroller unit (5); The microcontroller unit (5) is an MCU; the acceleration sensor module (6) collects acceleration data and performs analog-to-digital conversion before outputting the data to the microcontroller unit (5); the microcontroller unit (5) processes and stores the acceleration signal and then sends the signal to a host computer via the low-power Bluetooth module (7) and / or the wired serial port; the low-power Bluetooth module (7) also includes a sleep state and a working state; When the trigger signal output by the trigger wake-up module (3) disappears, the microcontroller unit (5) immediately enters the stop mode after sending the current data, and at the same time operates the low-power Bluetooth module (7) to enter the shutdown mode, at which time the self-powered sensor system enters a dormant state.

7. The TENG-based self-powered sensing system according to claim 1, characterized in that: The low-power Bluetooth module (7) uses an NB-LOT module to link to a 4G / 5G network provided by an operator, and the low-power Bluetooth module (7) outputs to a host computer, and the host computer is installed with LABVIEW software.

8. The TENG-based self-powered sensing system according to claim 1, characterized in that: The self-powered sensing system is applied to vibration monitoring.

9. The self-powered sensing system based on TENG according to claim 8, characterized in that: The self-powered sensing system is applied to bridge health monitoring, air conditioning fan monitoring and tower monitoring.

10. A sleep awakening method for a self-powered sensing system based on TENG according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, when the contact-separation friction nanogenerator (11) in the composite nanogenerator (1) captures vibration, the upper friction nanogenerator structure (111) and the lower friction nanogenerator structure (113) of the contact-separation friction nanogenerator (11) contact and separate under the elastic force of the spring (112), generate charge transfer under the action of electrostatic induction and output current to the trigger wake-up module (3) and the energy management module (2), respectively, the energy management module (2) smoothes the output power and outputs it to the battery charging module (4) for storage, the solar cell (12) in the composite nanogenerator (1) receives solar energy and outputs it to the energy management module (2), the energy management module (2) performs voltage stabilization and outputs it to the battery charging module (4) for storage; When the vibration reaches the untriggered threshold, the microcontroller unit (5) is in a dormant state; When the vibration reaches the trigger threshold, the trigger wake-up module (3) collects the trigger wake-up signal and outputs it to the microcontroller unit (5) to wake up the microcontroller unit (5), and at the same time, the battery charging module (4) provides power to the microcontroller unit (5) and the acceleration sensor module (6), and then enters step S2; S2, the acceleration sensor module (6) collects acceleration data and performs analog-to-digital conversion, and then outputs real-time acceleration data to the microcontroller unit (5), and the microcontroller unit (5) processes and stores the data and then sends the data to the upper computer through the low-power Bluetooth module (7) and / or the limited serial port. When the vibration intensity decreases below a set threshold, the process proceeds to step S3; S3, the trigger wake-up signal disappears, the microcontroller unit (5) immediately enters the stop mode after sending the current data, and at the same time operates the low-power Bluetooth module (7) to enter the shutdown mode, enters the sleep state, and returns to step S1.

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